Conventional typical resist materials are polymer based materials capable of forming amorphous thin films. For example, a line pattern of about 45 to 100 nm is formed by irradiating a resist thin film made by coating a substrate with a solution of a polymer resist material such as polymethyl methacrylate, polyhydroxy styrene with an acid dissociation reactive group, or polyalkyl methacrylate with ultraviolet, far ultraviolet, electron beam, extreme ultraviolet (EUV), and X-ray or the like.
However, because polymer based resists have a molecular weight as large as about 10,000 to 100,000 and also wide molecular weight distribution, in lithography using a polymer based resist, roughness occurs on a fine pattern surface; the pattern dimension becomes difficult to be controlled; and the yield decreases. Therefore, there is a limitation in miniaturization with lithography using a conventional polymer based resist material. In order to make a finer pattern, various low molecular weight resist materials have been proposed.
For example, an alkaline development type negative type radiation-sensitive composition (see Patent Literatures 1 and 2) using a low molecular weight polynuclear polyphenolic compound as a main component has been suggested. As a candidate of a low molecular weight resist material having high heat resistance, an alkaline development type, negative type radiation-sensitive composition (see Patent Literature 3 and Non Patent Literature 1) using a low molecular weight cyclic polyphenolic compound as a main component has also been suggested.
As a base compound of a resist material, a polyphenolic compound is known to be useful in imparting high heat resistance and improving the resolution or roughness of a resist pattern, in spite of its low molecular weight (see Non Patent Literature 2). Also, various polyphenols are used as raw materials for thermoplastic resins such as polycarbonate and polyarylate, raw materials for thermosetting resins such as epoxy resins, curing agents, modifiers, and the like (see Patent Literatures 4 and 5).
As resin raw materials or resin curing agents, fluorene compounds having a cardo structure are known to have various characteristics (optical characteristics, heat resistance, water resistance, moisture resistance, chemical resistance, electrical characteristics, mechanical characteristics, dimensional stability, etc.) improved by substitution with polyhydric phenol or the like (see Patent Literatures 6 to 9).